1. Field of the Invention
The present invention relates to an ultrasonic coagulation and cutting apparatus for gripping body tissue and performing coagulation using high frequency current and/or cutting using ultrasonic vibrations of the body tissue.
2. Description of the Related Art
In recent years, observations of body cavities and organs have been performed using endoscopes, an insertion portion of each endoscope being inserted into a body cavity. In addition, various treatments and therapies have also been performed under endoscopic observation. In cutting or coagulation of body tissue under endoscopic observation, an ultrasonic instrument for treatment or a diathermy instrument for treatment is used. The ultrasonic instrument transmits ultrasonic vibrations to body tissue to perform a treatment using frictional heat. The diathermy instrument supplies high frequency current to body tissue to perform a treatment using Joule heat.
Using ultrasonic vibrations, the ultrasonic instrument permits a tool for treatment to generate frictional heat, thus cutting body tissue while coagulating the tissue. The ultrasonic instrument performs coagulation and cutting as one action using frictional heat. Unfortunately, the ultrasonic instrument has a tendency that cutting power is reduced when coagulating power is increased. In particular, tissue cutting involving blood vessel clotting needs high coagulating power. However, reducing cutting power drastically leads to stress on a user. It is, therefore, difficult to realize high levels of both coagulation and cutting.
The diathermy instrument using high frequency current allows an energized electrode to come into contact with body tissue, thus performing cutting or coagulation of the tissue. Diathermy instruments are broadly classified into monopolar and bipolar types. The monopolar type instrument has the following structure: One of two dedicated terminals provided for a power supply unit for generating high frequency current is connected to an active electrode to be in contact with a target area of body tissue. The other terminal is connected to a feedback electrode to be in face contact with a wide range of a body surface except the target area.
The bipolar type instrument has the following structure: Two dedicated terminals provided for a power supply unit for generating high frequency current are connected to two active electrodes arranged in the instrument main body. Accordingly, the bipolar type needs no feedback electrode and is suitable for a treatment, such as blood vessel clotting, because a continuity path for the flow of current can be specified.
For example, when a treatment for blood vessel clotting is performed with the ultrasonic instrument, cutting is performed while coagulation is being performed. In the ultrasonic instrument, therefore, it is difficult to simultaneously realize high coagulating power and high cutting speed.
On the other hand, in the case where a treatment for blood vessel clotting is performed with the bipolar type diathermy instrument, although the bipolar type has high coagulating power, cutting is fundamentally performed using another instrument instead of the bipolar type diathermy instrument. In other words, a user has to often change the instrument. Disadvantageously, the operation is complicated.
Japanese Unexamined Patent Application Publication No. 2004-216180 discloses an ultrasonic cutting and coagulation apparatus capable of easily performing a treatment using ultrasonic vibrations and a treatment using high frequency current on body tissue in an appropriate manner. In this apparatus, a movable handle is operated to be closed such that a gripping member is brought into contact with a probe to grip body tissue. In this gripping state, when the treatment using ultrasonic vibrations is performed, a power supply for driving an ultrasonic transducer supplies driving current to the ultrasonic transducer. Consequently, the ultrasonic transducer is driven, thus transmitting ultrasonic vibrations generated by the ultrasonic transducer to the probe. Thus, the gripped body tissue is coagulated and cut.
On the other hand, when the treatment using high frequency current is performed in the gripping state, high frequency current is supplied from a high frequency power supply to either the gripping member or the probe, alternatively, to both of them. Consequently, the high frequency current flows from the gripping member or the probe to a counter electrode plate via the body tissue and is fed back to the high frequency power supply. Thus, the gripped tissue is cut or coagulated.